This section provides background information related to the present disclosure which is not necessarily prior art.
Such valves may be used to control the coolant flow of an internal combustion engine in order to guarantee an optimum coolant temperature in the fluid circuit according to load. In the event of a fault, such as for example a defective control of the valve, failure of the valve actuator or sticking of the valve, however an undesirable temperature rise of the coolant can occur and hence critical states which could damage the internal combustion engine. In order to prevent such faults in which the coolant temperature rises undesirably above a predefined temperature, the valve described in DE 10 2012 208 652 B3 has a fail-safe mechanism which, in the event of a fault, causes the valve body to move to a predefined position in which the coolant flow through the valve is maximal in order to counter overheating states in the coolant circuit. Such a fail-safe mechanism may also be called a reset device in the present case.
Since, in the valve described in DE 10 2012 208 652 B3, the valve body is fixedly connected to the positioning actuator, only actuators which are not self-locking may be used, since the self-locking would adversely affect the correct function of the fail-safe mechanism. Otherwise the fail-safe mechanism would have to be able to apply return moments which are sufficient to overcome the self-locking of the actuator, for which the torsion spring of the fail-safe mechanism would have to be configured correspondingly stiff and therefore relatively large. Even in the case of non-self-locking positioning actuators, the fail-safe mechanism of DE 10 2012 208 652 B3 or its torsion spring would however always have to work against the resistance or inertia moment of the actuator, for which the torsion spring must be designed correspondingly stiff and hence comparatively large.